1. Field of the Invention
The present invention relates generally to a plastic "knock-down" frame system that can be used to support shelving and other elements for carrying any desired item. More particularly this shelving system and more generally frame system, is of the type having modular components that can be easily assembled and disassembled for shipment, storage, and cleaning, and for modification of the configuration of a specific shelf or other item-supporting structure.
The frame system of the present invention may advantageously be used in food service, industrial, commercial, hospital, and similar fields for storage of any desired items.
2. Description of Pertinent Information
Shelving systems having adjustable height-shelves and so-called "knock-down" type shelving systems are known, and each has utility in many applications. Further, knock-down type shelving systems which also have adjustable height shelves have great utility in a number of applications, including the food service industry. For example, such shelving systems may be used for efficiently storing and transporting a wide variety of food items having various sizes, shapes and weights.
Generally speaking, in many such applications it is desirable to make the shelving system components of materials that do not corrode. It is also desirable to design such systems with a minimum number of crevices or other areas that might entrap contaminants. The systems should be designed for easy and effective cleaning.
Examples of "knock-down" type shelving systems which also have adjustable height shelves are shown in U.S. Reissue Pat. No. 28,293; and U.S. Pat. Nos. 3,523,508; 3,874,511; 4,138,953; and 3,604,369. These systems use a support post having a polygonal or circular cross-section, and at least one shelf having corner assemblies in which a complementary bore or hole is formed therethrough for receiving the support post. A wedge member is then disposed on each support post, between the support post and the respective sleeve of the corner assembly, for providing shelf support at a predetermined height on the post by a wedging action therebetween.
Although each of these systems has great utility in many applications, each suffers a drawback in that the shelf support system does not allow for the insertion or removal of an interior shelf within a plurality of shelves without the removal of adjacent shelves and at least partial disassembly of the overall shelving system. Further, as the corner assemblies of each shelf are designed with a sleeve therethrough for reception of the support posts, a tradeoff occurs between available shelf space and the stability of the shelving system. In a "cylindrical post" type support system (shown for example in U.S. Pat. Nos. 3,523,508; 3,874,511; and 4,138,953), a certain amount of shelf space is sacrificed by enlarging the circular diameter of the sleeve and post by moving the hole inwardly to assure the stability of the shelving system. In a "square-hole" type support system shown in U.S. Reissue Pat. No. 28,293, shelf space is sacrificed due to the geometry of the support post, which extends into the interior of the shelf.
In an attempt to solve one problem characteristic of systems such as those described above, shelving systems in which an interior shelf may be added or removed have been proposed. For example, U.S. Pat. Nos. 4,637,323; 4,615,278; 4,582,001; and 4,079,678 all relate to such systems which incorporate corner posts and cooperating shelves. Each shelf has a corner structure that engages a portion of the outer peripheral surfaces of a corner post and interengages with an element that embraces the remainder of the outer peripheral surface of the post in the region of the shelf. These systems are all characterized by difficult assembly since it is inherently difficult to align each of the embracing elements with each of the corner posts and shelf, and to connect all three components together at the same time.
As a result, as described in U.S. patent application Ser. No. 077,645 filed Jul. 24, 1987, and issued as U.S. Pat. No. 4,811,670, Mar. 24, 1989, the assignee of the present invention had developed an improved knock-down type shelving system in which the shelves may be easily adjusted to different heights, and wherein an interior shelf may be inserted or removed from the shelving system without removing adjacent shelves or at least partially disassembling the overall shelving system. The shelf support system disclosed in this application includes a support post having a generally right equilateral triangular cross-section. The right angular apex faces the exterior of the shelving system and the adjacent flat exterior sides of each support post are arranged parallel to the sides of the shelf, thus providing multi-directional stability for the assembly, particularly in the directions of the stress forces parallel to the sides of the shelf. A plastic wedge member is molded with contoured lips for embracing the interior face of the support post with a clip-on operation. The wedge member includes a viewing window, a shelf height indicator, and detent tabs, which, in cooperation with detent steps provided on the interior face of the support posts, adjustably locate the wedge member on the support post at a desired position. A bendable collar detachably engages a tapered corner bracket structurally associated with each corner of the shelf, and together therewith forms a sleeve around each support post, such that when the collar and corner bracket assembly is moved down the support post to seat on the wedge member, it securely and stably supports the shelf at the predetermined position on the support post by wedging action. While the system of U.S. Pat. No. 4,811,670 represents a substantial advance in the shelving art, still further improvements described below are desirable.